linux-kernel - Re: [PATCH tip/sched/core] mm/early_ioremap: Adjust early_ioremap system

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Date:   Fri, 16 Jun 2017 08:03:02 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH tip/sched/core] mm/early_ioremap: Adjust early_ioremap
 system_state check

On 6/16/2017 5:58 AM, Thomas Gleixner wrote:
> On Wed, 14 Jun 2017, Tom Lendacky wrote:
>> A recent change added a new system_state value, SYSTEM_SCHEDULING, which
>> exposed a warning issued by early_ioreamp() when the system_state was not
>> SYSTEM_BOOTING. Since early_ioremap() can be called when the system_state
>> is SYSTEM_SCHEDULING, the check to issue the warning is changed from
>> system_state != SYSTEM_BOOTING to system_state >= SYSTEM_RUNNING.
> 
> Errm, why is that early_ioremap() stuff called after we enabled the
> scheduler? At that point the regular ioremap stuff is long working.

As part of the SME support I'm decrypting the trampoline area during
set_real_mode_permissions().  Since it was still valid to use the
early_memremap()/early_ioremap() functions I chose to use those instead
of creating new ioremap functions to support encrypted or decrypted
mappings with and without write-protection.

I could look into adding new ioremap APIs, but their usage would be
limited to this one case.  Since the early_memremap() works I thought
that would be the best path and just adjust the WARNing condition.

Thanks,
Tom

> 
> Thanks,
> 
> 	tglx
> 
>